He told the Observer that he wanted to give Prime Minister Theresa May "an army" of pro-Brexit MPs that was "fully equipped and as big as possible".

He will target constituencies where most voters backed Brexit, but which are currently represented by an MP that favoured Remain, offering upto £5,000 per candidate. With nearly 140 such constituencies, Hosking could end up spending close to £700,000 on the campaign.

Announcing the plans on his Brexit Express website, Hosking said: "The British voter, having delivered a clear answer to the question put to them on Europe, now deserve to see that decision delivered upon. That's the essence of direct democracy.

"We have seen that the institutions of the EU are determined to make life as difficult as possible for the UK and, indeed, have told us that 'Brexit cannot be a success'.

"I believe it can be and realistically the only way to ensure 'no backsliding on Brexit' is to back the Prime Minister to the fullest extent. I'm asking Brexit voters to put aside their party allegiances temporarily, lend Brexit their votes and climb aboard the Brexit Express."

Much of the money will be spent on candidates in traditional Labour heartlands of the north and the Midlands.

Hosking, who founded Marathon Asset Management, said he wanted a "full, national Brexit" rather than a "City of London Brexit".

"Brexit has been labelled a divisive issue. It is my belief that it can be a unifying one," he said.

"That, at least for the moment, a bigger prize is at stake; one that only Theresa May is likely to be able to deliver. In my mind, the prize is quite simply the sovereign future of this independent-minded democracy.

"Britain has always come together when that is what is at stake. Let's do it again. No backsliding over Brexit."